1. Field of the Invention
The present invention relates to a power supply control apparatus, having a power saving mode, and a control method thereof.
2. Description of the Related Art
Conventionally, apparatuses having a power saving mode have had 2 modes: a normal mode in which the intended normal operations of the apparatus are performed; and a power saving mode in which power consumption is inhibited and normal operations waited upon.
There exist apparatuses for which, when in the power saving mode, in order to reduce power consumption as much as possible, current is only passed to a part which detects a trigger for returning from the power saving mode to the normal mode, and power supply to the rest of the parts is stopped.
On the other hand, to reflect the rise in calls for power consumption reduction with a power saving mode, a power switch is provided on the side of a commercial power supply input (hereinafter referred to as “the AC side”), and when power supply to the parts other than the part which detects the trigger for returning from the power saving mode to the normal mode is stopped, the AC side is disconnected from the parts by this power switch being turned off. This is because when, in a state in which the commercial power supply (AC side) is connected to a power supply unit, when the power supply to the apparatus is disconnected, power is consumed within the power supply unit. A mechanical relay which is low cost and can handle a large current is used as the switch for disconnecting the power supply on the AC side in this way. However, for this kind of mechanical relay, a mechanical life and an electrical life are set, and power supply control apparatuses, which perform control processing so not to turn off (disconnect) the mechanical relay for a set period of time in order to satisfy these lifetimes, have been proposed. (refer to Japanese Patent Laid-Open No. 2009-15649).
In the power supply control apparatus disclosed in Japanese Patent Laid-Open No. 2009-15649, even in the case where the power saving mode is returned to in order to process a status query packet from, for example, an management server, it is necessary to keep the mechanical relay (the connection to the AC side) on for a specific period of time. Also, even in the case where a job such as one that doesn't include printing (for example, referencing data that was saved in the power supply control apparatus) is executed, it is necessary to keep the mechanical relay ON for a specific period of time. However, because of, for example, the fact that power savings in the aforementioned part that detects the trigger have improved, power consumption due to the maintaining of the “ON” state of the mechanical relay has become a problem.
Also, in order to improve power savings in cases such as when the state of the device is queried and when a job that doesn't include printing is executed, it is possible to consider methods of passing current to a LAN controller and a CPU without turning on the mechanical relay. However, in order to do this it is necessary to increase the rated output capacity of the power supply unit that operates during the power saving mode. A problem existed that if the rated output capacity of the power supply unit is increased, because the power conversion efficiency is degraded when only low power relative to the rated output capacity is used, the power usage on the AC side increases in the power saving mode in which current is only passed to the trigger detection part.